iotools component for maccrad

[dacoex]

See: #272 for reason.

Previous discussion in #271

@wholmgren I hope I got this git thing right... But anyway, we are in a separate branch than master.

[wholmgren]

Thanks. Some general comments:

I'd prefer that we tackle one format per pull request. This will make each one go faster and be less likely to become stale and neglected.

It looks like you're duplicating the new code in the pvlib-python/io branch instead of adding to it and that's what led to the merge conflict. To build on what's already in the pvlib-python/io branch, you'll need to fetch pvlib-python's io branch and then rebase your changes on it (or merge it into your branch). Depending on your git experience, it might be easier to make a fresh clone, checkout the io branch, and copy over the files related to macc or pvsyst.

There are probably too many data files and they're probably too long. We only want to include the bare minimum of data required to test the code and to let users run an example or two.

The iotools/iotools.py module should be renamed iotools/util.py to avoid confusion.

I don't think we should create a dependency on the timezonefinder package. That's probably best left to users to implement themselves, if desired.